1. Field of the Invention
The present invention relates to a carbonaceous heat source composition for a non-combustion-type smoking article.
2. Description of the Related Art
Tobacco is a typical flavor-generating material for which the flavor in the smoke (aerosol) generated by combusting the tobacco leaves is enjoyed through gustatory or olfactory organs of human.
In recent years, in place of, or in addition to, tobacco, non-combustion-type smoking articles have been developed for enjoying the flavor and taste of tobacco and for enjoying the aerosol, without combusting the tobacco leaves. These non-combustion-type smoking articles comprise a heat source which is a heat-generating member mounted on the tip and a flavor-generating member in which a flavoring component is held in an appropriate substrate. The heat source is physically separated from the flavor-generating member generating the aerosol containing the flavoring component. In the smoking articles of this type, the heat source is combusted, and the heat of combustion heats the flavor-generating member without combustion to generate an aerosol containing the flavoring component. The smoker inhales the aerosol to enjoy the flavor.
A carbonaceous heat source is used exclusively as the heat source. Various proposals have been presented for decreasing the amount of carbon monoxide that is generated during combustion of the heat source.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2-215373 discloses a heat source body containing a metal carbide, carbon and a binder is disclosed in, for example. In this heat source body, the particle diameter and the specific surface area of the metal carbide are controlled to enhance the combustion rate of the heat source and to decrease the amount of carbon monoxide. Jpn. Pat. Appln. KOKAI Publication No. 3-272675 discloses a heat source body containing a metal nitride, carbon and a binder. In this heat source body, the metal nitride forms a metal oxide by combustion, and the metal oxide promotes the conversion of carbon monoxide into carbon dioxide, thereby decreasing the amount of carbon monoxide. U.S. Pat. No. 4,881,556 discloses a carbonaceous fuel element containing carbon and a binder. In this fuel element, the density and the shape of the fuel element are changed so as to enhance the combustibility of the fuel element, thereby decreasing the amount of carbon monoxide. Further, U.S. Pat. No. 5,595,577 discloses a carbonaceous heat source containing a metal oxide. In this heat source, the amount of carbon monoxide is decreased by the metal oxide deposited on the heat source. Further, U.S. Patent Application Publication No. US 2004/0173229 A1 discloses a combustible material containing an ultra fine metal catalyst. In this combustible material, the metal catalyst converts carbon monoxide to carbon dioxide, thereby decreasing the amount of carbon monoxide. Jpn. Pat. Appln. KOKAI Publication No. 10-179112 discloses a heat source composition containing carbon, a binder, a non-combustible graphite and potassium. In this heat source composition, the amount of carbon monoxide is decreased by controlling the amount of potassium.
These prior art carbonaceous heat sources are still insufficient in terms of decreasing the amount of carbon monoxide. In addition, the heat source using a catalyst for oxidizing carbon monoxide involves the reliability problem of the smoking article. Also, as a means for decreasing the amount of carbon monoxide introduced into the mouth, it is conceivable to provide the filter mounted on the smoking article with a ventilation effect. However, the filter ventilation greatly changes the flavor and taste of the article by the dilution with air.